<html>
<head>
  <title>06-B+树索引</title>
  <basefont face="微软雅黑" size="2" />
  <meta http-equiv="Content-Type" content="text/html;charset=utf-8" />
  <meta name="exporter-version" content="YXBJ Windows/600646 (zh-CN, DDL); Windows/6.1.1 (Win64);"/>
  <meta name="content-class" content="yinxiang.markdown"/>
  <style>
    body, td {
      font-family: 微软雅黑;
      font-size: 10pt;
    }
  </style>
</head>
<body>
<a name="661"/>
<h1>06-B+树索引</h1>

<div><span><div style="font-size: 14px; margin: 0; padding: 0; width: 100%;"><h2 style="line-height: 160%; box-sizing: content-box; font-weight: 700; font-size: 34px; border-bottom: 1px solid #dbdbdb; color: #333;">B+树索引</h2>
<p style="line-height: 160%; box-sizing: content-box; margin: 10px 0; color: #333;">InnoDB数据页由7个部分组成，各个数据页组可以组成一个<strong style="line-height: 160%; box-sizing: content-box; font-weight: 700;">双向链表</strong>，每个数据页中的记录会按照主键值从小到大的顺序组成一个<strong style="line-height: 160%; box-sizing: content-box; font-weight: 700;">单向链表</strong>，每个数据页都会为存储在它里边的记录生成一个<strong style="line-height: 160%; box-sizing: content-box; font-weight: 700;">页目录（Page Directory）</strong>，在通过主键查找某条记录的时候可以在页目录中使用二分法快速定位到对应的<strong style="line-height: 160%; box-sizing: content-box; font-weight: 700;">槽（Slot）</strong>，然后再遍历该槽对应分组中的记录即可快速找到指定的记录。页和记录的关系示意图如下：<br/>
<img src="06-B+树索引_files/1.jpg" type="image/jpeg" data-filename="1.jpg"/><br/>
接下来为了方便查看，以聚簇索引为例，c1列为主键，c2和c3为普通列，将行记录格式省略了一些信息，简写成下图：<br/>
<img src="06-B+树索引_files/1 [1].jpg" type="image/jpeg" data-filename="1.jpg"/></p>
<p style="line-height: 160%; box-sizing: content-box; margin: 10px 0; color: #333;">把一些记录放到页里边的示意图就是：<br/>
<img src="06-B+树索引_files/1 [2].jpg" type="image/jpeg" data-filename="1.jpg"/></p>
<p style="line-height: 160%; box-sizing: content-box; margin: 10px 0; color: #333;">B+树结构图：<br/>
<img src="06-B+树索引_files/1 [3].jpg" type="image/jpeg" data-filename="1.jpg"/><br/>
假设一个索引页中最多可以存储4条目录项记录，一个索引页中最多可以存储3条用户记录，则B+树如下图：<br/>
<img src="06-B+树索引_files/1 [4].jpg" type="image/jpeg" data-filename="1.jpg"/></p>
<ul style="line-height: 160%; box-sizing: content-box; display: block; list-style-type: disc; padding-left: 30px; margin: 6px 0 10px; color: #333;">
<li style="line-height: 160%; box-sizing: content-box; position: relative;"><strong style="line-height: 160%; box-sizing: content-box; font-weight: 700;">根节点</strong>：B+树最上边的节点称为根节点；</li>
<li style="line-height: 160%; box-sizing: content-box; position: relative;"><strong style="line-height: 160%; box-sizing: content-box; font-weight: 700;">叶子节点</strong>：B+树最底层，用户存储实际用户记录的节点；</li>
<li style="line-height: 160%; box-sizing: content-box; position: relative;"><strong style="line-height: 160%; box-sizing: content-box; font-weight: 700;">非叶子节点</strong>：B+树用来存储目录项的节点；</li>
</ul>
<p style="line-height: 160%; box-sizing: content-box; margin: 10px 0; color: #333;"><strong style="line-height: 160%; box-sizing: content-box; font-weight: 700;">目录项记录和用户记录的区别：</strong></p>
<ul style="line-height: 160%; box-sizing: content-box; display: block; list-style-type: disc; padding-left: 30px; margin: 6px 0 10px; color: #333;">
<li style="line-height: 160%; box-sizing: content-box; position: relative;">目录项记录的记录头信息中的record_type值是1（非叶子节点记录），用户记录的record_type值是0（普通记录）；</li>
<li style="line-height: 160%; box-sizing: content-box; position: relative;">目录项记录只有主键值（该目录项所对应的数据页中最小记录的主键值）和页的编号两个列。而普通的用户记录的列是用户自己定义的，可能包含很多列，另外还有InnoDB自己添加的隐藏列；</li>
<li style="line-height: 160%; box-sizing: content-box; position: relative;">min_rec_mask，B+树的每层非叶子节点中的最小记录都会添加该标记；</li>
</ul>
<p style="line-height: 160%; box-sizing: content-box; margin: 10px 0; color: #333;">除了上述几点外，这两者就没啥差别了，它们用的是一样的数据页（页面类型都是0x45BF，这个属性在File Header中，忘了的话可以翻到前边的文章看），页的组成结构也是一样一样的（就是我们前边介绍过的7个部分），都会为主键值生成Page Directory（页目录），从而在按照主键值进行查找时可以使用二分法来加快查询速度。</p>
<p style="line-height: 160%; box-sizing: content-box; margin: 10px 0; color: #333;">那么根据主键值查找一条用户记录大致需要3个步骤：</p>
<ul style="line-height: 160%; box-sizing: content-box; display: block; list-style-type: disc; padding-left: 30px; margin: 6px 0 10px; color: #333;">
<li style="line-height: 160%; box-sizing: content-box; position: relative;">确定目录项记录页；</li>
<li style="line-height: 160%; box-sizing: content-box; position: relative;">通过目录项记录页确定用户记录真实所在的页；</li>
<li style="line-height: 160%; box-sizing: content-box; position: relative;">在真实存储用户记录的页中定位到具体的记录；</li>
</ul>
<p style="line-height: 160%; box-sizing: content-box; margin: 10px 0; color: #333;">一个4层的B+树，假设所有存放用户记录的叶子节点代表的数据页可以存放100条用户记录，所有存放目录项记录的非叶子节点代表的数据页可以存放1000条目录项记录，那么：</p>
<ul style="line-height: 160%; box-sizing: content-box; display: block; list-style-type: disc; padding-left: 30px; margin: 6px 0 10px; color: #333;">
<li style="line-height: 160%; box-sizing: content-box; position: relative;">如果B+树只有1层，也就是只有1个用于存放用户记录的节点，最多能存放100条记录；</li>
<li style="line-height: 160%; box-sizing: content-box; position: relative;">如果B+树有2层，最多能存放1000×100=100000条记录；</li>
<li style="line-height: 160%; box-sizing: content-box; position: relative;">如果B+树有3层，最多能存放1000×1000×100=100000000条记录；</li>
<li style="line-height: 160%; box-sizing: content-box; position: relative;">如果B+树有4层，最多能存放1000×1000×1000×100=100000000000条记录。哇咔咔～这么多的记录！！！</li>
</ul>
<p style="line-height: 160%; box-sizing: content-box; margin: 10px 0; color: #333;">在通过主键值去查找某条记录最多只需要做4个页面内的查找（3个目录项页和一个用户记录页），又因为在每个页面内有所谓的Page Directory（页目录），所以在页面内也可以通过二分法实现快速定位记录！</p>
<h3 style="line-height: 160%; box-sizing: content-box; font-weight: 700; font-size: 27px; color: #333;">聚簇索引</h3>
<p style="line-height: 160%; box-sizing: content-box; margin: 10px 0; color: #333;">上边介绍的B+树本身就是一个目录，或者说本身就是一个索引。它有两个特点：</p>
<ol style="line-height: 160%; box-sizing: content-box; display: block; padding-left: 30px; margin: 6px 0 10px; color: #333; list-style-type: decimal;">
<li style="line-height: 160%; box-sizing: content-box;">使用记录主键值的大小进行记录和页的排序，这包括三个方面的含义：</li>
</ol>
<ul style="line-height: 160%; box-sizing: content-box; display: block; list-style-type: disc; padding-left: 30px; margin: 6px 0 10px; color: #333;">
<li style="line-height: 160%; box-sizing: content-box; position: relative;">页内的记录是按照主键的大小顺序排成一个单向链表；</li>
<li style="line-height: 160%; box-sizing: content-box; position: relative;">各个存放用户记录的页也是根据页中用户记录的主键大小顺序排成一个双向链表；</li>
<li style="line-height: 160%; box-sizing: content-box; position: relative;">存放目录项记录的页分为不同的层次，在同一层次中的页也是根据页中目录项记录的主键大小顺序排成一个双向链表；</li>
</ul>
<ol start="2" style="line-height: 160%; box-sizing: content-box; display: block; padding-left: 30px; margin: 6px 0 10px; color: #333; list-style-type: decimal;">
<li style="line-height: 160%; box-sizing: content-box;">B+树的叶子节点存储的是完整的用户记录：所谓完整的用户记录，就是指这个记录中存储了所有列的值（包括隐藏列）。</li>
</ol>
<p style="line-height: 160%; box-sizing: content-box; margin: 10px 0; color: #333;">我们把具有这两种特性的B+树称为<strong style="line-height: 160%; box-sizing: content-box; font-weight: 700;">聚簇索引</strong>，<strong style="line-height: 160%; box-sizing: content-box; font-weight: 700;">所有完整的用户记录都存放在这个聚簇索引的叶子节点处</strong>。这种聚簇索引并不需要我们在MySQL语句中显式的使用INDEX语句去创建（后边会介绍索引相关的语句），<strong style="line-height: 160%; box-sizing: content-box; font-weight: 700;">InnoDB存储引擎会自动的为我们创建聚簇索引</strong>。另外有趣的一点是，在InnoDB存储引擎中，聚簇索引就是数据的存储方式（所有的用户记录都存储在了叶子节点），也就是所谓的索引即数据，数据即索引。</p>
<h3 style="line-height: 160%; box-sizing: content-box; font-weight: 700; font-size: 27px; color: #333;">二级索引</h3>
<p style="line-height: 160%; box-sizing: content-box; margin: 10px 0; color: #333;">不同的B+树中的数据采用不同的排序规则。比如用c2列的大小作为数据页、页中记录的排序规则，再建一棵B+树，效果如下图所示：<br/>
<img src="06-B+树索引_files/1 [5].jpg" type="image/jpeg" data-filename="1.jpg"/></p>
<p style="line-height: 160%; box-sizing: content-box; margin: 10px 0; color: #333;">这个B+树与上边介绍的聚簇索引有几处不同：</p>
<ul style="line-height: 160%; box-sizing: content-box; display: block; list-style-type: disc; padding-left: 30px; margin: 6px 0 10px; color: #333;">
<li style="line-height: 160%; box-sizing: content-box; position: relative;">使用记录c2列的大小进行记录和页的排序；</li>
<li style="line-height: 160%; box-sizing: content-box; position: relative;">B+树的叶子节点存储的不是完整的而用户记录，而是c2列+主键这两个列的值；</li>
<li style="line-height: 160%; box-sizing: content-box; position: relative;">目录项记录中不再是主键+页号的搭配，而变成了c2列+主键（用于c2列相同时，用主键对记录排序）+页号的搭配；</li>
</ul>
<p style="line-height: 160%; box-sizing: content-box; margin: 10px 0; color: #333;">那么由于二级索引的叶子节点钟只存储了c2列和主键值，如果想要得到完整的用户记录，需要再根据主键值去聚簇索引中再查找一遍完整的用户记录。<strong style="line-height: 160%; box-sizing: content-box; font-weight: 700;">这个过程也被称为回表</strong>！</p>
<p style="line-height: 160%; box-sizing: content-box; margin: 10px 0; color: #333;">因为这种按照非主键列建立的B+树需要一次回表操作才可以定位到完整的用户记录，所以这种B+树也被称为<strong style="line-height: 160%; box-sizing: content-box; font-weight: 700;">二级索引（英文名secondary index），或者辅助索引</strong>。</p>
<h3 style="line-height: 160%; box-sizing: content-box; font-weight: 700; font-size: 27px; color: #333;">联合索引</h3>
<p style="line-height: 160%; box-sizing: content-box; margin: 10px 0; color: #333;">也可以同时以多个列的大小作为排序规则，也就是同时为多个列建立索引，比方说我们想让B+树按照c2和c3列的大小进行排序，这个包含两层含义：</p>
<ul style="line-height: 160%; box-sizing: content-box; display: block; list-style-type: disc; padding-left: 30px; margin: 6px 0 10px; color: #333;">
<li style="line-height: 160%; box-sizing: content-box; position: relative;">先把各记录和页按照c2列进行排序；</li>
<li style="line-height: 160%; box-sizing: content-box; position: relative;">在记录的c2列相同的情况下，采用c3列进行排序；<br/>
<img src="06-B+树索引_files/1 [6].jpg" type="image/jpeg" data-filename="1.jpg"/></li>
</ul>
<h3 style="line-height: 160%; box-sizing: content-box; font-weight: 700; font-size: 27px; color: #333;">InnoDB的B+树索引的注意事项</h3>
<h4 style="line-height: 160%; box-sizing: content-box; font-size: 20px; color: #333;">1. 根页面万年不动窝</h4>
<p style="line-height: 160%; box-sizing: content-box; margin: 10px 0; color: #333;">B+树的形成过程是这样的：</p>
<ul style="line-height: 160%; box-sizing: content-box; display: block; list-style-type: disc; padding-left: 30px; margin: 6px 0 10px; color: #333;">
<li style="line-height: 160%; box-sizing: content-box; position: relative;">每当为某个表创建一个B+树索引（聚簇索引不是人为创建的，默认就有）的时候，都会为这个索引创建一个根节点页面。最开始表中没有数据的时候，每个B+树索引对应的根节点中既没有用户记录，也没有目录项记录；</li>
<li style="line-height: 160%; box-sizing: content-box; position: relative;">随后向表中插入用户记录时，先把用户记录存储到这个<strong style="line-height: 160%; box-sizing: content-box; font-weight: 700;">根节点</strong>中；</li>
<li style="line-height: 160%; box-sizing: content-box; position: relative;">当根节点中的可用空间用完时继续插入行记录，此时会将根节点中的所有记录复制到一个新分配的页，比如页a中，然后对这个新页进行<strong style="line-height: 160%; box-sizing: content-box; font-weight: 700;">页分裂</strong>的操作，得到另一个新页，记作页b。这时新插入的记录根据主键值（也就是聚簇索引中的主键值，二级索引中对应的索引列的值）的大小就会被分配到页a或者页b中，而根节点便升级为存储目录项记录的页。</li>
</ul>
<p style="line-height: 160%; box-sizing: content-box; margin: 10px 0; color: #333;"><strong style="line-height: 160%; box-sizing: content-box; font-weight: 700;">一个B+树索引的根节点自诞生之日起，便不会再移动。这样只要我们对某个表建立一个索引，那么它的根节点的页号便会被记录到某个地方，然后凡是InnoDB存储引擎需要用到这个索引的时候，都会从那个固定的地方取出根节点的页号，从而来访问这个索引。</strong></p>
<h4 style="line-height: 160%; box-sizing: content-box; font-size: 20px; color: #333;">2. 内节点中目录项记录的唯一性</h4>
<p style="line-height: 160%; box-sizing: content-box; margin: 10px 0; color: #333;">为了让新插入记录能找到自己在那个页里，我们需要保证在B+树的同一层内节点的目录项记录除页号这个字段以外是唯一的。所以对于二级索引的内节点的目录项记录的内容实际上是由三个部分构成的：</p>
<ul style="line-height: 160%; box-sizing: content-box; display: block; list-style-type: disc; padding-left: 30px; margin: 6px 0 10px; color: #333;">
<li style="line-height: 160%; box-sizing: content-box; position: relative;">索引列的值</li>
<li style="line-height: 160%; box-sizing: content-box; position: relative;">主键值</li>
<li style="line-height: 160%; box-sizing: content-box; position: relative;">页号</li>
</ul>
<h4 style="line-height: 160%; box-sizing: content-box; font-size: 20px; color: #333;">3. 一个页面最少存储2条记录</h4>
<h4 style="line-height: 160%; box-sizing: content-box; font-size: 20px; color: #333;">索引基本语法</h4>
<ol style="line-height: 160%; box-sizing: content-box; display: block; padding-left: 30px; margin: 6px 0 10px; color: #333; list-style-type: decimal;">
<li style="line-height: 160%; box-sizing: content-box;">
<p style="line-height: 160%; box-sizing: content-box; margin: 10px 0; color: #333;">创建表的时候指定需要建立索引的单个列或者建立联合索引的多个列：<br/>
CREATE TALBE 表名 (<br/>
各种列的信息 ··· ,</p>
<p style="line-height: 160%; box-sizing: content-box; margin: 10px 0; color: #333;">[KEY|INDEX] 索引名 (需要被索引的单个列或多个列)<br/>
)；</p>
</li>
<li style="line-height: 160%; box-sizing: content-box;">
<p style="line-height: 160%; box-sizing: content-box; margin: 10px 0; color: #333;">修改表结构的时候添加索引：<br/>
ALTER TABLE 表名 ADD [INDEX|KEY] 索引名 (需要被索引的单个列或多个列)；</p>
</li>
<li style="line-height: 160%; box-sizing: content-box;">
<p style="line-height: 160%; box-sizing: content-box; margin: 10px 0; color: #333;">修改表结构的时候删除索引：<br/>
ALTER TABLE 表名 DROP [INDEX|KEY] 索引名;</p>
</li>
</ol>
</div><center style="display:none !important;visibility:collapse !important;height:0 !important;white-space:nowrap;width:100%;overflow:hidden">%23%23%20B%2B%E6%A0%91%E7%B4%A2%E5%BC%95%0A%0AInnoDB%E6%95%B0%E6%8D%AE%E9%A1%B5%E7%94%B17%E4%B8%AA%E9%83%A8%E5%88%86%E7%BB%84%E6%88%90%EF%BC%8C%E5%90%84%E4%B8%AA%E6%95%B0%E6%8D%AE%E9%A1%B5%E7%BB%84%E5%8F%AF%E4%BB%A5%E7%BB%84%E6%88%90%E4%B8%80%E4%B8%AA**%E5%8F%8C%E5%90%91%E9%93%BE%E8%A1%A8**%EF%BC%8C%E6%AF%8F%E4%B8%AA%E6%95%B0%E6%8D%AE%E9%A1%B5%E4%B8%AD%E7%9A%84%E8%AE%B0%E5%BD%95%E4%BC%9A%E6%8C%89%E7%85%A7%E4%B8%BB%E9%94%AE%E5%80%BC%E4%BB%8E%E5%B0%8F%E5%88%B0%E5%A4%A7%E7%9A%84%E9%A1%BA%E5%BA%8F%E7%BB%84%E6%88%90%E4%B8%80%E4%B8%AA**%E5%8D%95%E5%90%91%E9%93%BE%E8%A1%A8**%EF%BC%8C%E6%AF%8F%E4%B8%AA%E6%95%B0%E6%8D%AE%E9%A1%B5%E9%83%BD%E4%BC%9A%E4%B8%BA%E5%AD%98%E5%82%A8%E5%9C%A8%E5%AE%83%E9%87%8C%E8%BE%B9%E7%9A%84%E8%AE%B0%E5%BD%95%E7%94%9F%E6%88%90%E4%B8%80%E4%B8%AA**%E9%A1%B5%E7%9B%AE%E5%BD%95%EF%BC%88Page%20Directory%EF%BC%89**%EF%BC%8C%E5%9C%A8%E9%80%9A%E8%BF%87%E4%B8%BB%E9%94%AE%E6%9F%A5%E6%89%BE%E6%9F%90%E6%9D%A1%E8%AE%B0%E5%BD%95%E7%9A%84%E6%97%B6%E5%80%99%E5%8F%AF%E4%BB%A5%E5%9C%A8%E9%A1%B5%E7%9B%AE%E5%BD%95%E4%B8%AD%E4%BD%BF%E7%94%A8%E4%BA%8C%E5%88%86%E6%B3%95%E5%BF%AB%E9%80%9F%E5%AE%9A%E4%BD%8D%E5%88%B0%E5%AF%B9%E5%BA%94%E7%9A%84**%E6%A7%BD%EF%BC%88Slot%EF%BC%89**%EF%BC%8C%E7%84%B6%E5%90%8E%E5%86%8D%E9%81%8D%E5%8E%86%E8%AF%A5%E6%A7%BD%E5%AF%B9%E5%BA%94%E5%88%86%E7%BB%84%E4%B8%AD%E7%9A%84%E8%AE%B0%E5%BD%95%E5%8D%B3%E5%8F%AF%E5%BF%AB%E9%80%9F%E6%89%BE%E5%88%B0%E6%8C%87%E5%AE%9A%E7%9A%84%E8%AE%B0%E5%BD%95%E3%80%82%E9%A1%B5%E5%92%8C%E8%AE%B0%E5%BD%95%E7%9A%84%E5%85%B3%E7%B3%BB%E7%A4%BA%E6%84%8F%E5%9B%BE%E5%A6%82%E4%B8%8B%EF%BC%9A%0A!%5B3d3b7def4c83c4de57ed8a1468598526.jpeg%5D(en-resource%3A%2F%2Fdatabase%2F663%3A0)%0A%E6%8E%A5%E4%B8%8B%E6%9D%A5%E4%B8%BA%E4%BA%86%E6%96%B9%E4%BE%BF%E6%9F%A5%E7%9C%8B%EF%BC%8C%E4%BB%A5%E8%81%9A%E7%B0%87%E7%B4%A2%E5%BC%95%E4%B8%BA%E4%BE%8B%EF%BC%8Cc1%E5%88%97%E4%B8%BA%E4%B8%BB%E9%94%AE%EF%BC%8Cc2%E5%92%8Cc3%E4%B8%BA%E6%99%AE%E9%80%9A%E5%88%97%EF%BC%8C%E5%B0%86%E8%A1%8C%E8%AE%B0%E5%BD%95%E6%A0%BC%E5%BC%8F%E7%9C%81%E7%95%A5%E4%BA%86%E4%B8%80%E4%BA%9B%E4%BF%A1%E6%81%AF%EF%BC%8C%E7%AE%80%E5%86%99%E6%88%90%E4%B8%8B%E5%9B%BE%EF%BC%9A%0A!%5B82f6cc4c55423cc6951f267bcbe3b7d1.jpeg%5D(en-resource%3A%2F%2Fdatabase%2F665%3A0)%0A%0A%E6%8A%8A%E4%B8%80%E4%BA%9B%E8%AE%B0%E5%BD%95%E6%94%BE%E5%88%B0%E9%A1%B5%E9%87%8C%E8%BE%B9%E7%9A%84%E7%A4%BA%E6%84%8F%E5%9B%BE%E5%B0%B1%E6%98%AF%EF%BC%9A%0A!%5B0d13e76104f293d0aeae36ab7c576acd.jpeg%5D(en-resource%3A%2F%2Fdatabase%2F667%3A0)%0A%0A%0AB%2B%E6%A0%91%E7%BB%93%E6%9E%84%E5%9B%BE%EF%BC%9A%0A!%5Bd20b932c01612a878201b152a74d2189.jpeg%5D(en-resource%3A%2F%2Fdatabase%2F669%3A0)%0A%E5%81%87%E8%AE%BE%E4%B8%80%E4%B8%AA%E7%B4%A2%E5%BC%95%E9%A1%B5%E4%B8%AD%E6%9C%80%E5%A4%9A%E5%8F%AF%E4%BB%A5%E5%AD%98%E5%82%A84%E6%9D%A1%E7%9B%AE%E5%BD%95%E9%A1%B9%E8%AE%B0%E5%BD%95%EF%BC%8C%E4%B8%80%E4%B8%AA%E7%B4%A2%E5%BC%95%E9%A1%B5%E4%B8%AD%E6%9C%80%E5%A4%9A%E5%8F%AF%E4%BB%A5%E5%AD%98%E5%82%A83%E6%9D%A1%E7%94%A8%E6%88%B7%E8%AE%B0%E5%BD%95%EF%BC%8C%E5%88%99B%2B%E6%A0%91%E5%A6%82%E4%B8%8B%E5%9B%BE%EF%BC%9A%0A!%5Bc34f3aacf0c5cff64d2c23f9dce34fe6.jpeg%5D(en-resource%3A%2F%2Fdatabase%2F671%3A0)%0A%0A*%20**%E6%A0%B9%E8%8A%82%E7%82%B9**%EF%BC%9AB%2B%E6%A0%91%E6%9C%80%E4%B8%8A%E8%BE%B9%E7%9A%84%E8%8A%82%E7%82%B9%E7%A7%B0%E4%B8%BA%E6%A0%B9%E8%8A%82%E7%82%B9%EF%BC%9B%0A*%20**%E5%8F%B6%E5%AD%90%E8%8A%82%E7%82%B9**%EF%BC%9AB%2B%E6%A0%91%E6%9C%80%E5%BA%95%E5%B1%82%EF%BC%8C%E7%94%A8%E6%88%B7%E5%AD%98%E5%82%A8%E5%AE%9E%E9%99%85%E7%94%A8%E6%88%B7%E8%AE%B0%E5%BD%95%E7%9A%84%E8%8A%82%E7%82%B9%EF%BC%9B%0A*%20**%E9%9D%9E%E5%8F%B6%E5%AD%90%E8%8A%82%E7%82%B9**%EF%BC%9AB%2B%E6%A0%91%E7%94%A8%E6%9D%A5%E5%AD%98%E5%82%A8%E7%9B%AE%E5%BD%95%E9%A1%B9%E7%9A%84%E8%8A%82%E7%82%B9%EF%BC%9B%0A%0A**%E7%9B%AE%E5%BD%95%E9%A1%B9%E8%AE%B0%E5%BD%95%E5%92%8C%E7%94%A8%E6%88%B7%E8%AE%B0%E5%BD%95%E7%9A%84%E5%8C%BA%E5%88%AB%EF%BC%9A**%0A%0A*%20%E7%9B%AE%E5%BD%95%E9%A1%B9%E8%AE%B0%E5%BD%95%E7%9A%84%E8%AE%B0%E5%BD%95%E5%A4%B4%E4%BF%A1%E6%81%AF%E4%B8%AD%E7%9A%84record_type%E5%80%BC%E6%98%AF1%EF%BC%88%E9%9D%9E%E5%8F%B6%E5%AD%90%E8%8A%82%E7%82%B9%E8%AE%B0%E5%BD%95%EF%BC%89%EF%BC%8C%E7%94%A8%E6%88%B7%E8%AE%B0%E5%BD%95%E7%9A%84record_type%E5%80%BC%E6%98%AF0%EF%BC%88%E6%99%AE%E9%80%9A%E8%AE%B0%E5%BD%95%EF%BC%89%EF%BC%9B%0A*%20%E7%9B%AE%E5%BD%95%E9%A1%B9%E8%AE%B0%E5%BD%95%E5%8F%AA%E6%9C%89%E4%B8%BB%E9%94%AE%E5%80%BC%EF%BC%88%E8%AF%A5%E7%9B%AE%E5%BD%95%E9%A1%B9%E6%89%80%E5%AF%B9%E5%BA%94%E7%9A%84%E6%95%B0%E6%8D%AE%E9%A1%B5%E4%B8%AD%E6%9C%80%E5%B0%8F%E8%AE%B0%E5%BD%95%E7%9A%84%E4%B8%BB%E9%94%AE%E5%80%BC%EF%BC%89%E5%92%8C%E9%A1%B5%E7%9A%84%E7%BC%96%E5%8F%B7%E4%B8%A4%E4%B8%AA%E5%88%97%E3%80%82%E8%80%8C%E6%99%AE%E9%80%9A%E7%9A%84%E7%94%A8%E6%88%B7%E8%AE%B0%E5%BD%95%E7%9A%84%E5%88%97%E6%98%AF%E7%94%A8%E6%88%B7%E8%87%AA%E5%B7%B1%E5%AE%9A%E4%B9%89%E7%9A%84%EF%BC%8C%E5%8F%AF%E8%83%BD%E5%8C%85%E5%90%AB%E5%BE%88%E5%A4%9A%E5%88%97%EF%BC%8C%E5%8F%A6%E5%A4%96%E8%BF%98%E6%9C%89InnoDB%E8%87%AA%E5%B7%B1%E6%B7%BB%E5%8A%A0%E7%9A%84%E9%9A%90%E8%97%8F%E5%88%97%EF%BC%9B%0A*%20min_rec_mask%EF%BC%8CB%2B%E6%A0%91%E7%9A%84%E6%AF%8F%E5%B1%82%E9%9D%9E%E5%8F%B6%E5%AD%90%E8%8A%82%E7%82%B9%E4%B8%AD%E7%9A%84%E6%9C%80%E5%B0%8F%E8%AE%B0%E5%BD%95%E9%83%BD%E4%BC%9A%E6%B7%BB%E5%8A%A0%E8%AF%A5%E6%A0%87%E8%AE%B0%EF%BC%9B%0A%0A%0A%E9%99%A4%E4%BA%86%E4%B8%8A%E8%BF%B0%E5%87%A0%E7%82%B9%E5%A4%96%EF%BC%8C%E8%BF%99%E4%B8%A4%E8%80%85%E5%B0%B1%E6%B2%A1%E5%95%A5%E5%B7%AE%E5%88%AB%E4%BA%86%EF%BC%8C%E5%AE%83%E4%BB%AC%E7%94%A8%E7%9A%84%E6%98%AF%E4%B8%80%E6%A0%B7%E7%9A%84%E6%95%B0%E6%8D%AE%E9%A1%B5%EF%BC%88%E9%A1%B5%E9%9D%A2%E7%B1%BB%E5%9E%8B%E9%83%BD%E6%98%AF0x45BF%EF%BC%8C%E8%BF%99%E4%B8%AA%E5%B1%9E%E6%80%A7%E5%9C%A8File%20Header%E4%B8%AD%EF%BC%8C%E5%BF%98%E4%BA%86%E7%9A%84%E8%AF%9D%E5%8F%AF%E4%BB%A5%E7%BF%BB%E5%88%B0%E5%89%8D%E8%BE%B9%E7%9A%84%E6%96%87%E7%AB%A0%E7%9C%8B%EF%BC%89%EF%BC%8C%E9%A1%B5%E7%9A%84%E7%BB%84%E6%88%90%E7%BB%93%E6%9E%84%E4%B9%9F%E6%98%AF%E4%B8%80%E6%A0%B7%E4%B8%80%E6%A0%B7%E7%9A%84%EF%BC%88%E5%B0%B1%E6%98%AF%E6%88%91%E4%BB%AC%E5%89%8D%E8%BE%B9%E4%BB%8B%E7%BB%8D%E8%BF%87%E7%9A%847%E4%B8%AA%E9%83%A8%E5%88%86%EF%BC%89%EF%BC%8C%E9%83%BD%E4%BC%9A%E4%B8%BA%E4%B8%BB%E9%94%AE%E5%80%BC%E7%94%9F%E6%88%90Page%20Directory%EF%BC%88%E9%A1%B5%E7%9B%AE%E5%BD%95%EF%BC%89%EF%BC%8C%E4%BB%8E%E8%80%8C%E5%9C%A8%E6%8C%89%E7%85%A7%E4%B8%BB%E9%94%AE%E5%80%BC%E8%BF%9B%E8%A1%8C%E6%9F%A5%E6%89%BE%E6%97%B6%E5%8F%AF%E4%BB%A5%E4%BD%BF%E7%94%A8%E4%BA%8C%E5%88%86%E6%B3%95%E6%9D%A5%E5%8A%A0%E5%BF%AB%E6%9F%A5%E8%AF%A2%E9%80%9F%E5%BA%A6%E3%80%82%0A%0A%E9%82%A3%E4%B9%88%E6%A0%B9%E6%8D%AE%E4%B8%BB%E9%94%AE%E5%80%BC%E6%9F%A5%E6%89%BE%E4%B8%80%E6%9D%A1%E7%94%A8%E6%88%B7%E8%AE%B0%E5%BD%95%E5%A4%A7%E8%87%B4%E9%9C%80%E8%A6%813%E4%B8%AA%E6%AD%A5%E9%AA%A4%EF%BC%9A%0A%0A*%20%E7%A1%AE%E5%AE%9A%E7%9B%AE%E5%BD%95%E9%A1%B9%E8%AE%B0%E5%BD%95%E9%A1%B5%EF%BC%9B%0A*%20%E9%80%9A%E8%BF%87%E7%9B%AE%E5%BD%95%E9%A1%B9%E8%AE%B0%E5%BD%95%E9%A1%B5%E7%A1%AE%E5%AE%9A%E7%94%A8%E6%88%B7%E8%AE%B0%E5%BD%95%E7%9C%9F%E5%AE%9E%E6%89%80%E5%9C%A8%E7%9A%84%E9%A1%B5%EF%BC%9B%0A*%20%E5%9C%A8%E7%9C%9F%E5%AE%9E%E5%AD%98%E5%82%A8%E7%94%A8%E6%88%B7%E8%AE%B0%E5%BD%95%E7%9A%84%E9%A1%B5%E4%B8%AD%E5%AE%9A%E4%BD%8D%E5%88%B0%E5%85%B7%E4%BD%93%E7%9A%84%E8%AE%B0%E5%BD%95%EF%BC%9B%0A%0A%E4%B8%80%E4%B8%AA4%E5%B1%82%E7%9A%84B%2B%E6%A0%91%EF%BC%8C%E5%81%87%E8%AE%BE%E6%89%80%E6%9C%89%E5%AD%98%E6%94%BE%E7%94%A8%E6%88%B7%E8%AE%B0%E5%BD%95%E7%9A%84%E5%8F%B6%E5%AD%90%E8%8A%82%E7%82%B9%E4%BB%A3%E8%A1%A8%E7%9A%84%E6%95%B0%E6%8D%AE%E9%A1%B5%E5%8F%AF%E4%BB%A5%E5%AD%98%E6%94%BE100%E6%9D%A1%E7%94%A8%E6%88%B7%E8%AE%B0%E5%BD%95%EF%BC%8C%E6%89%80%E6%9C%89%E5%AD%98%E6%94%BE%E7%9B%AE%E5%BD%95%E9%A1%B9%E8%AE%B0%E5%BD%95%E7%9A%84%E9%9D%9E%E5%8F%B6%E5%AD%90%E8%8A%82%E7%82%B9%E4%BB%A3%E8%A1%A8%E7%9A%84%E6%95%B0%E6%8D%AE%E9%A1%B5%E5%8F%AF%E4%BB%A5%E5%AD%98%E6%94%BE1000%E6%9D%A1%E7%9B%AE%E5%BD%95%E9%A1%B9%E8%AE%B0%E5%BD%95%EF%BC%8C%E9%82%A3%E4%B9%88%EF%BC%9A%0A%0A*%20%E5%A6%82%E6%9E%9CB%2B%E6%A0%91%E5%8F%AA%E6%9C%891%E5%B1%82%EF%BC%8C%E4%B9%9F%E5%B0%B1%E6%98%AF%E5%8F%AA%E6%9C%891%E4%B8%AA%E7%94%A8%E4%BA%8E%E5%AD%98%E6%94%BE%E7%94%A8%E6%88%B7%E8%AE%B0%E5%BD%95%E7%9A%84%E8%8A%82%E7%82%B9%EF%BC%8C%E6%9C%80%E5%A4%9A%E8%83%BD%E5%AD%98%E6%94%BE100%E6%9D%A1%E8%AE%B0%E5%BD%95%EF%BC%9B%0A*%20%E5%A6%82%E6%9E%9CB%2B%E6%A0%91%E6%9C%892%E5%B1%82%EF%BC%8C%E6%9C%80%E5%A4%9A%E8%83%BD%E5%AD%98%E6%94%BE1000%C3%97100%3D100000%E6%9D%A1%E8%AE%B0%E5%BD%95%EF%BC%9B%0A*%20%E5%A6%82%E6%9E%9CB%2B%E6%A0%91%E6%9C%893%E5%B1%82%EF%BC%8C%E6%9C%80%E5%A4%9A%E8%83%BD%E5%AD%98%E6%94%BE1000%C3%971000%C3%97100%3D100000000%E6%9D%A1%E8%AE%B0%E5%BD%95%EF%BC%9B%0A*%20%E5%A6%82%E6%9E%9CB%2B%E6%A0%91%E6%9C%894%E5%B1%82%EF%BC%8C%E6%9C%80%E5%A4%9A%E8%83%BD%E5%AD%98%E6%94%BE1000%C3%971000%C3%971000%C3%97100%3D100000000000%E6%9D%A1%E8%AE%B0%E5%BD%95%E3%80%82%E5%93%87%E5%92%94%E5%92%94%EF%BD%9E%E8%BF%99%E4%B9%88%E5%A4%9A%E7%9A%84%E8%AE%B0%E5%BD%95%EF%BC%81%EF%BC%81%EF%BC%81%0A%0A%E5%9C%A8%E9%80%9A%E8%BF%87%E4%B8%BB%E9%94%AE%E5%80%BC%E5%8E%BB%E6%9F%A5%E6%89%BE%E6%9F%90%E6%9D%A1%E8%AE%B0%E5%BD%95%E6%9C%80%E5%A4%9A%E5%8F%AA%E9%9C%80%E8%A6%81%E5%81%9A4%E4%B8%AA%E9%A1%B5%E9%9D%A2%E5%86%85%E7%9A%84%E6%9F%A5%E6%89%BE%EF%BC%883%E4%B8%AA%E7%9B%AE%E5%BD%95%E9%A1%B9%E9%A1%B5%E5%92%8C%E4%B8%80%E4%B8%AA%E7%94%A8%E6%88%B7%E8%AE%B0%E5%BD%95%E9%A1%B5%EF%BC%89%EF%BC%8C%E5%8F%88%E5%9B%A0%E4%B8%BA%E5%9C%A8%E6%AF%8F%E4%B8%AA%E9%A1%B5%E9%9D%A2%E5%86%85%E6%9C%89%E6%89%80%E8%B0%93%E7%9A%84Page%20Directory%EF%BC%88%E9%A1%B5%E7%9B%AE%E5%BD%95%EF%BC%89%EF%BC%8C%E6%89%80%E4%BB%A5%E5%9C%A8%E9%A1%B5%E9%9D%A2%E5%86%85%E4%B9%9F%E5%8F%AF%E4%BB%A5%E9%80%9A%E8%BF%87%E4%BA%8C%E5%88%86%E6%B3%95%E5%AE%9E%E7%8E%B0%E5%BF%AB%E9%80%9F%E5%AE%9A%E4%BD%8D%E8%AE%B0%E5%BD%95%EF%BC%81%0A%0A%23%23%23%20%E8%81%9A%E7%B0%87%E7%B4%A2%E5%BC%95%0A%0A%E4%B8%8A%E8%BE%B9%E4%BB%8B%E7%BB%8D%E7%9A%84B%2B%E6%A0%91%E6%9C%AC%E8%BA%AB%E5%B0%B1%E6%98%AF%E4%B8%80%E4%B8%AA%E7%9B%AE%E5%BD%95%EF%BC%8C%E6%88%96%E8%80%85%E8%AF%B4%E6%9C%AC%E8%BA%AB%E5%B0%B1%E6%98%AF%E4%B8%80%E4%B8%AA%E7%B4%A2%E5%BC%95%E3%80%82%E5%AE%83%E6%9C%89%E4%B8%A4%E4%B8%AA%E7%89%B9%E7%82%B9%EF%BC%9A%0A1.%20%E4%BD%BF%E7%94%A8%E8%AE%B0%E5%BD%95%E4%B8%BB%E9%94%AE%E5%80%BC%E7%9A%84%E5%A4%A7%E5%B0%8F%E8%BF%9B%E8%A1%8C%E8%AE%B0%E5%BD%95%E5%92%8C%E9%A1%B5%E7%9A%84%E6%8E%92%E5%BA%8F%EF%BC%8C%E8%BF%99%E5%8C%85%E6%8B%AC%E4%B8%89%E4%B8%AA%E6%96%B9%E9%9D%A2%E7%9A%84%E5%90%AB%E4%B9%89%EF%BC%9A%0A*%20%E9%A1%B5%E5%86%85%E7%9A%84%E8%AE%B0%E5%BD%95%E6%98%AF%E6%8C%89%E7%85%A7%E4%B8%BB%E9%94%AE%E7%9A%84%E5%A4%A7%E5%B0%8F%E9%A1%BA%E5%BA%8F%E6%8E%92%E6%88%90%E4%B8%80%E4%B8%AA%E5%8D%95%E5%90%91%E9%93%BE%E8%A1%A8%EF%BC%9B%0A*%20%E5%90%84%E4%B8%AA%E5%AD%98%E6%94%BE%E7%94%A8%E6%88%B7%E8%AE%B0%E5%BD%95%E7%9A%84%E9%A1%B5%E4%B9%9F%E6%98%AF%E6%A0%B9%E6%8D%AE%E9%A1%B5%E4%B8%AD%E7%94%A8%E6%88%B7%E8%AE%B0%E5%BD%95%E7%9A%84%E4%B8%BB%E9%94%AE%E5%A4%A7%E5%B0%8F%E9%A1%BA%E5%BA%8F%E6%8E%92%E6%88%90%E4%B8%80%E4%B8%AA%E5%8F%8C%E5%90%91%E9%93%BE%E8%A1%A8%EF%BC%9B%0A*%20%E5%AD%98%E6%94%BE%E7%9B%AE%E5%BD%95%E9%A1%B9%E8%AE%B0%E5%BD%95%E7%9A%84%E9%A1%B5%E5%88%86%E4%B8%BA%E4%B8%8D%E5%90%8C%E7%9A%84%E5%B1%82%E6%AC%A1%EF%BC%8C%E5%9C%A8%E5%90%8C%E4%B8%80%E5%B1%82%E6%AC%A1%E4%B8%AD%E7%9A%84%E9%A1%B5%E4%B9%9F%E6%98%AF%E6%A0%B9%E6%8D%AE%E9%A1%B5%E4%B8%AD%E7%9B%AE%E5%BD%95%E9%A1%B9%E8%AE%B0%E5%BD%95%E7%9A%84%E4%B8%BB%E9%94%AE%E5%A4%A7%E5%B0%8F%E9%A1%BA%E5%BA%8F%E6%8E%92%E6%88%90%E4%B8%80%E4%B8%AA%E5%8F%8C%E5%90%91%E9%93%BE%E8%A1%A8%EF%BC%9B%0A%0A2.%20B%2B%E6%A0%91%E7%9A%84%E5%8F%B6%E5%AD%90%E8%8A%82%E7%82%B9%E5%AD%98%E5%82%A8%E7%9A%84%E6%98%AF%E5%AE%8C%E6%95%B4%E7%9A%84%E7%94%A8%E6%88%B7%E8%AE%B0%E5%BD%95%EF%BC%9A%E6%89%80%E8%B0%93%E5%AE%8C%E6%95%B4%E7%9A%84%E7%94%A8%E6%88%B7%E8%AE%B0%E5%BD%95%EF%BC%8C%E5%B0%B1%E6%98%AF%E6%8C%87%E8%BF%99%E4%B8%AA%E8%AE%B0%E5%BD%95%E4%B8%AD%E5%AD%98%E5%82%A8%E4%BA%86%E6%89%80%E6%9C%89%E5%88%97%E7%9A%84%E5%80%BC%EF%BC%88%E5%8C%85%E6%8B%AC%E9%9A%90%E8%97%8F%E5%88%97%EF%BC%89%E3%80%82%0A%0A%E6%88%91%E4%BB%AC%E6%8A%8A%E5%85%B7%E6%9C%89%E8%BF%99%E4%B8%A4%E7%A7%8D%E7%89%B9%E6%80%A7%E7%9A%84B%2B%E6%A0%91%E7%A7%B0%E4%B8%BA**%E8%81%9A%E7%B0%87%E7%B4%A2%E5%BC%95**%EF%BC%8C**%E6%89%80%E6%9C%89%E5%AE%8C%E6%95%B4%E7%9A%84%E7%94%A8%E6%88%B7%E8%AE%B0%E5%BD%95%E9%83%BD%E5%AD%98%E6%94%BE%E5%9C%A8%E8%BF%99%E4%B8%AA%E8%81%9A%E7%B0%87%E7%B4%A2%E5%BC%95%E7%9A%84%E5%8F%B6%E5%AD%90%E8%8A%82%E7%82%B9%E5%A4%84**%E3%80%82%E8%BF%99%E7%A7%8D%E8%81%9A%E7%B0%87%E7%B4%A2%E5%BC%95%E5%B9%B6%E4%B8%8D%E9%9C%80%E8%A6%81%E6%88%91%E4%BB%AC%E5%9C%A8MySQL%E8%AF%AD%E5%8F%A5%E4%B8%AD%E6%98%BE%E5%BC%8F%E7%9A%84%E4%BD%BF%E7%94%A8INDEX%E8%AF%AD%E5%8F%A5%E5%8E%BB%E5%88%9B%E5%BB%BA%EF%BC%88%E5%90%8E%E8%BE%B9%E4%BC%9A%E4%BB%8B%E7%BB%8D%E7%B4%A2%E5%BC%95%E7%9B%B8%E5%85%B3%E7%9A%84%E8%AF%AD%E5%8F%A5%EF%BC%89%EF%BC%8C**InnoDB%E5%AD%98%E5%82%A8%E5%BC%95%E6%93%8E%E4%BC%9A%E8%87%AA%E5%8A%A8%E7%9A%84%E4%B8%BA%E6%88%91%E4%BB%AC%E5%88%9B%E5%BB%BA%E8%81%9A%E7%B0%87%E7%B4%A2%E5%BC%95**%E3%80%82%E5%8F%A6%E5%A4%96%E6%9C%89%E8%B6%A3%E7%9A%84%E4%B8%80%E7%82%B9%E6%98%AF%EF%BC%8C%E5%9C%A8InnoDB%E5%AD%98%E5%82%A8%E5%BC%95%E6%93%8E%E4%B8%AD%EF%BC%8C%E8%81%9A%E7%B0%87%E7%B4%A2%E5%BC%95%E5%B0%B1%E6%98%AF%E6%95%B0%E6%8D%AE%E7%9A%84%E5%AD%98%E5%82%A8%E6%96%B9%E5%BC%8F%EF%BC%88%E6%89%80%E6%9C%89%E7%9A%84%E7%94%A8%E6%88%B7%E8%AE%B0%E5%BD%95%E9%83%BD%E5%AD%98%E5%82%A8%E5%9C%A8%E4%BA%86%E5%8F%B6%E5%AD%90%E8%8A%82%E7%82%B9%EF%BC%89%EF%BC%8C%E4%B9%9F%E5%B0%B1%E6%98%AF%E6%89%80%E8%B0%93%E7%9A%84%E7%B4%A2%E5%BC%95%E5%8D%B3%E6%95%B0%E6%8D%AE%EF%BC%8C%E6%95%B0%E6%8D%AE%E5%8D%B3%E7%B4%A2%E5%BC%95%E3%80%82%0A%0A%23%23%23%20%E4%BA%8C%E7%BA%A7%E7%B4%A2%E5%BC%95%0A%0A%E4%B8%8D%E5%90%8C%E7%9A%84B%2B%E6%A0%91%E4%B8%AD%E7%9A%84%E6%95%B0%E6%8D%AE%E9%87%87%E7%94%A8%E4%B8%8D%E5%90%8C%E7%9A%84%E6%8E%92%E5%BA%8F%E8%A7%84%E5%88%99%E3%80%82%E6%AF%94%E5%A6%82%E7%94%A8c2%E5%88%97%E7%9A%84%E5%A4%A7%E5%B0%8F%E4%BD%9C%E4%B8%BA%E6%95%B0%E6%8D%AE%E9%A1%B5%E3%80%81%E9%A1%B5%E4%B8%AD%E8%AE%B0%E5%BD%95%E7%9A%84%E6%8E%92%E5%BA%8F%E8%A7%84%E5%88%99%EF%BC%8C%E5%86%8D%E5%BB%BA%E4%B8%80%E6%A3%B5B%2B%E6%A0%91%EF%BC%8C%E6%95%88%E6%9E%9C%E5%A6%82%E4%B8%8B%E5%9B%BE%E6%89%80%E7%A4%BA%EF%BC%9A%0A!%5Bca72b1c10457c9ede4e3dc5ddb0947fc.jpeg%5D(en-resource%3A%2F%2Fdatabase%2F673%3A0)%0A%0A%E8%BF%99%E4%B8%AAB%2B%E6%A0%91%E4%B8%8E%E4%B8%8A%E8%BE%B9%E4%BB%8B%E7%BB%8D%E7%9A%84%E8%81%9A%E7%B0%87%E7%B4%A2%E5%BC%95%E6%9C%89%E5%87%A0%E5%A4%84%E4%B8%8D%E5%90%8C%EF%BC%9A%0A%0A*%20%E4%BD%BF%E7%94%A8%E8%AE%B0%E5%BD%95c2%E5%88%97%E7%9A%84%E5%A4%A7%E5%B0%8F%E8%BF%9B%E8%A1%8C%E8%AE%B0%E5%BD%95%E5%92%8C%E9%A1%B5%E7%9A%84%E6%8E%92%E5%BA%8F%EF%BC%9B%0A*%20B%2B%E6%A0%91%E7%9A%84%E5%8F%B6%E5%AD%90%E8%8A%82%E7%82%B9%E5%AD%98%E5%82%A8%E7%9A%84%E4%B8%8D%E6%98%AF%E5%AE%8C%E6%95%B4%E7%9A%84%E8%80%8C%E7%94%A8%E6%88%B7%E8%AE%B0%E5%BD%95%EF%BC%8C%E8%80%8C%E6%98%AFc2%E5%88%97%2B%E4%B8%BB%E9%94%AE%E8%BF%99%E4%B8%A4%E4%B8%AA%E5%88%97%E7%9A%84%E5%80%BC%EF%BC%9B%0A*%20%E7%9B%AE%E5%BD%95%E9%A1%B9%E8%AE%B0%E5%BD%95%E4%B8%AD%E4%B8%8D%E5%86%8D%E6%98%AF%E4%B8%BB%E9%94%AE%2B%E9%A1%B5%E5%8F%B7%E7%9A%84%E6%90%AD%E9%85%8D%EF%BC%8C%E8%80%8C%E5%8F%98%E6%88%90%E4%BA%86c2%E5%88%97%2B%E4%B8%BB%E9%94%AE%EF%BC%88%E7%94%A8%E4%BA%8Ec2%E5%88%97%E7%9B%B8%E5%90%8C%E6%97%B6%EF%BC%8C%E7%94%A8%E4%B8%BB%E9%94%AE%E5%AF%B9%E8%AE%B0%E5%BD%95%E6%8E%92%E5%BA%8F%EF%BC%89%2B%E9%A1%B5%E5%8F%B7%E7%9A%84%E6%90%AD%E9%85%8D%EF%BC%9B%0A%0A%E9%82%A3%E4%B9%88%E7%94%B1%E4%BA%8E%E4%BA%8C%E7%BA%A7%E7%B4%A2%E5%BC%95%E7%9A%84%E5%8F%B6%E5%AD%90%E8%8A%82%E7%82%B9%E9%92%9F%E5%8F%AA%E5%AD%98%E5%82%A8%E4%BA%86c2%E5%88%97%E5%92%8C%E4%B8%BB%E9%94%AE%E5%80%BC%EF%BC%8C%E5%A6%82%E6%9E%9C%E6%83%B3%E8%A6%81%E5%BE%97%E5%88%B0%E5%AE%8C%E6%95%B4%E7%9A%84%E7%94%A8%E6%88%B7%E8%AE%B0%E5%BD%95%EF%BC%8C%E9%9C%80%E8%A6%81%E5%86%8D%E6%A0%B9%E6%8D%AE%E4%B8%BB%E9%94%AE%E5%80%BC%E5%8E%BB%E8%81%9A%E7%B0%87%E7%B4%A2%E5%BC%95%E4%B8%AD%E5%86%8D%E6%9F%A5%E6%89%BE%E4%B8%80%E9%81%8D%E5%AE%8C%E6%95%B4%E7%9A%84%E7%94%A8%E6%88%B7%E8%AE%B0%E5%BD%95%E3%80%82**%E8%BF%99%E4%B8%AA%E8%BF%87%E7%A8%8B%E4%B9%9F%E8%A2%AB%E7%A7%B0%E4%B8%BA%E5%9B%9E%E8%A1%A8**%EF%BC%81%0A%0A%E5%9B%A0%E4%B8%BA%E8%BF%99%E7%A7%8D%E6%8C%89%E7%85%A7%E9%9D%9E%E4%B8%BB%E9%94%AE%E5%88%97%E5%BB%BA%E7%AB%8B%E7%9A%84B%2B%E6%A0%91%E9%9C%80%E8%A6%81%E4%B8%80%E6%AC%A1%E5%9B%9E%E8%A1%A8%E6%93%8D%E4%BD%9C%E6%89%8D%E5%8F%AF%E4%BB%A5%E5%AE%9A%E4%BD%8D%E5%88%B0%E5%AE%8C%E6%95%B4%E7%9A%84%E7%94%A8%E6%88%B7%E8%AE%B0%E5%BD%95%EF%BC%8C%E6%89%80%E4%BB%A5%E8%BF%99%E7%A7%8DB%2B%E6%A0%91%E4%B9%9F%E8%A2%AB%E7%A7%B0%E4%B8%BA**%E4%BA%8C%E7%BA%A7%E7%B4%A2%E5%BC%95%EF%BC%88%E8%8B%B1%E6%96%87%E5%90%8Dsecondary%20index%EF%BC%89%EF%BC%8C%E6%88%96%E8%80%85%E8%BE%85%E5%8A%A9%E7%B4%A2%E5%BC%95**%E3%80%82%0A%0A%0A%23%23%23%20%E8%81%94%E5%90%88%E7%B4%A2%E5%BC%95%0A%0A%E4%B9%9F%E5%8F%AF%E4%BB%A5%E5%90%8C%E6%97%B6%E4%BB%A5%E5%A4%9A%E4%B8%AA%E5%88%97%E7%9A%84%E5%A4%A7%E5%B0%8F%E4%BD%9C%E4%B8%BA%E6%8E%92%E5%BA%8F%E8%A7%84%E5%88%99%EF%BC%8C%E4%B9%9F%E5%B0%B1%E6%98%AF%E5%90%8C%E6%97%B6%E4%B8%BA%E5%A4%9A%E4%B8%AA%E5%88%97%E5%BB%BA%E7%AB%8B%E7%B4%A2%E5%BC%95%EF%BC%8C%E6%AF%94%E6%96%B9%E8%AF%B4%E6%88%91%E4%BB%AC%E6%83%B3%E8%AE%A9B%2B%E6%A0%91%E6%8C%89%E7%85%A7c2%E5%92%8Cc3%E5%88%97%E7%9A%84%E5%A4%A7%E5%B0%8F%E8%BF%9B%E8%A1%8C%E6%8E%92%E5%BA%8F%EF%BC%8C%E8%BF%99%E4%B8%AA%E5%8C%85%E5%90%AB%E4%B8%A4%E5%B1%82%E5%90%AB%E4%B9%89%EF%BC%9A%0A%0A*%20%E5%85%88%E6%8A%8A%E5%90%84%E8%AE%B0%E5%BD%95%E5%92%8C%E9%A1%B5%E6%8C%89%E7%85%A7c2%E5%88%97%E8%BF%9B%E8%A1%8C%E6%8E%92%E5%BA%8F%EF%BC%9B%0A*%20%E5%9C%A8%E8%AE%B0%E5%BD%95%E7%9A%84c2%E5%88%97%E7%9B%B8%E5%90%8C%E7%9A%84%E6%83%85%E5%86%B5%E4%B8%8B%EF%BC%8C%E9%87%87%E7%94%A8c3%E5%88%97%E8%BF%9B%E8%A1%8C%E6%8E%92%E5%BA%8F%EF%BC%9B%0A!%5Bed6a0cdffbfa4d35c03ca8fceb95c77b.jpeg%5D(en-resource%3A%2F%2Fdatabase%2F675%3A0)%0A%0A%23%23%23%20InnoDB%E7%9A%84B%2B%E6%A0%91%E7%B4%A2%E5%BC%95%E7%9A%84%E6%B3%A8%E6%84%8F%E4%BA%8B%E9%A1%B9%0A%23%23%23%23%201.%20%E6%A0%B9%E9%A1%B5%E9%9D%A2%E4%B8%87%E5%B9%B4%E4%B8%8D%E5%8A%A8%E7%AA%9D%0AB%2B%E6%A0%91%E7%9A%84%E5%BD%A2%E6%88%90%E8%BF%87%E7%A8%8B%E6%98%AF%E8%BF%99%E6%A0%B7%E7%9A%84%EF%BC%9A%0A%0A*%20%E6%AF%8F%E5%BD%93%E4%B8%BA%E6%9F%90%E4%B8%AA%E8%A1%A8%E5%88%9B%E5%BB%BA%E4%B8%80%E4%B8%AAB%2B%E6%A0%91%E7%B4%A2%E5%BC%95%EF%BC%88%E8%81%9A%E7%B0%87%E7%B4%A2%E5%BC%95%E4%B8%8D%E6%98%AF%E4%BA%BA%E4%B8%BA%E5%88%9B%E5%BB%BA%E7%9A%84%EF%BC%8C%E9%BB%98%E8%AE%A4%E5%B0%B1%E6%9C%89%EF%BC%89%E7%9A%84%E6%97%B6%E5%80%99%EF%BC%8C%E9%83%BD%E4%BC%9A%E4%B8%BA%E8%BF%99%E4%B8%AA%E7%B4%A2%E5%BC%95%E5%88%9B%E5%BB%BA%E4%B8%80%E4%B8%AA%E6%A0%B9%E8%8A%82%E7%82%B9%E9%A1%B5%E9%9D%A2%E3%80%82%E6%9C%80%E5%BC%80%E5%A7%8B%E8%A1%A8%E4%B8%AD%E6%B2%A1%E6%9C%89%E6%95%B0%E6%8D%AE%E7%9A%84%E6%97%B6%E5%80%99%EF%BC%8C%E6%AF%8F%E4%B8%AAB%2B%E6%A0%91%E7%B4%A2%E5%BC%95%E5%AF%B9%E5%BA%94%E7%9A%84%E6%A0%B9%E8%8A%82%E7%82%B9%E4%B8%AD%E6%97%A2%E6%B2%A1%E6%9C%89%E7%94%A8%E6%88%B7%E8%AE%B0%E5%BD%95%EF%BC%8C%E4%B9%9F%E6%B2%A1%E6%9C%89%E7%9B%AE%E5%BD%95%E9%A1%B9%E8%AE%B0%E5%BD%95%EF%BC%9B%0A*%20%E9%9A%8F%E5%90%8E%E5%90%91%E8%A1%A8%E4%B8%AD%E6%8F%92%E5%85%A5%E7%94%A8%E6%88%B7%E8%AE%B0%E5%BD%95%E6%97%B6%EF%BC%8C%E5%85%88%E6%8A%8A%E7%94%A8%E6%88%B7%E8%AE%B0%E5%BD%95%E5%AD%98%E5%82%A8%E5%88%B0%E8%BF%99%E4%B8%AA**%E6%A0%B9%E8%8A%82%E7%82%B9**%E4%B8%AD%EF%BC%9B%0A*%20%E5%BD%93%E6%A0%B9%E8%8A%82%E7%82%B9%E4%B8%AD%E7%9A%84%E5%8F%AF%E7%94%A8%E7%A9%BA%E9%97%B4%E7%94%A8%E5%AE%8C%E6%97%B6%E7%BB%A7%E7%BB%AD%E6%8F%92%E5%85%A5%E8%A1%8C%E8%AE%B0%E5%BD%95%EF%BC%8C%E6%AD%A4%E6%97%B6%E4%BC%9A%E5%B0%86%E6%A0%B9%E8%8A%82%E7%82%B9%E4%B8%AD%E7%9A%84%E6%89%80%E6%9C%89%E8%AE%B0%E5%BD%95%E5%A4%8D%E5%88%B6%E5%88%B0%E4%B8%80%E4%B8%AA%E6%96%B0%E5%88%86%E9%85%8D%E7%9A%84%E9%A1%B5%EF%BC%8C%E6%AF%94%E5%A6%82%E9%A1%B5a%E4%B8%AD%EF%BC%8C%E7%84%B6%E5%90%8E%E5%AF%B9%E8%BF%99%E4%B8%AA%E6%96%B0%E9%A1%B5%E8%BF%9B%E8%A1%8C**%E9%A1%B5%E5%88%86%E8%A3%82**%E7%9A%84%E6%93%8D%E4%BD%9C%EF%BC%8C%E5%BE%97%E5%88%B0%E5%8F%A6%E4%B8%80%E4%B8%AA%E6%96%B0%E9%A1%B5%EF%BC%8C%E8%AE%B0%E4%BD%9C%E9%A1%B5b%E3%80%82%E8%BF%99%E6%97%B6%E6%96%B0%E6%8F%92%E5%85%A5%E7%9A%84%E8%AE%B0%E5%BD%95%E6%A0%B9%E6%8D%AE%E4%B8%BB%E9%94%AE%E5%80%BC%EF%BC%88%E4%B9%9F%E5%B0%B1%E6%98%AF%E8%81%9A%E7%B0%87%E7%B4%A2%E5%BC%95%E4%B8%AD%E7%9A%84%E4%B8%BB%E9%94%AE%E5%80%BC%EF%BC%8C%E4%BA%8C%E7%BA%A7%E7%B4%A2%E5%BC%95%E4%B8%AD%E5%AF%B9%E5%BA%94%E7%9A%84%E7%B4%A2%E5%BC%95%E5%88%97%E7%9A%84%E5%80%BC%EF%BC%89%E7%9A%84%E5%A4%A7%E5%B0%8F%E5%B0%B1%E4%BC%9A%E8%A2%AB%E5%88%86%E9%85%8D%E5%88%B0%E9%A1%B5a%E6%88%96%E8%80%85%E9%A1%B5b%E4%B8%AD%EF%BC%8C%E8%80%8C%E6%A0%B9%E8%8A%82%E7%82%B9%E4%BE%BF%E5%8D%87%E7%BA%A7%E4%B8%BA%E5%AD%98%E5%82%A8%E7%9B%AE%E5%BD%95%E9%A1%B9%E8%AE%B0%E5%BD%95%E7%9A%84%E9%A1%B5%E3%80%82%0A%0A**%E4%B8%80%E4%B8%AAB%2B%E6%A0%91%E7%B4%A2%E5%BC%95%E7%9A%84%E6%A0%B9%E8%8A%82%E7%82%B9%E8%87%AA%E8%AF%9E%E7%94%9F%E4%B9%8B%E6%97%A5%E8%B5%B7%EF%BC%8C%E4%BE%BF%E4%B8%8D%E4%BC%9A%E5%86%8D%E7%A7%BB%E5%8A%A8%E3%80%82%E8%BF%99%E6%A0%B7%E5%8F%AA%E8%A6%81%E6%88%91%E4%BB%AC%E5%AF%B9%E6%9F%90%E4%B8%AA%E8%A1%A8%E5%BB%BA%E7%AB%8B%E4%B8%80%E4%B8%AA%E7%B4%A2%E5%BC%95%EF%BC%8C%E9%82%A3%E4%B9%88%E5%AE%83%E7%9A%84%E6%A0%B9%E8%8A%82%E7%82%B9%E7%9A%84%E9%A1%B5%E5%8F%B7%E4%BE%BF%E4%BC%9A%E8%A2%AB%E8%AE%B0%E5%BD%95%E5%88%B0%E6%9F%90%E4%B8%AA%E5%9C%B0%E6%96%B9%EF%BC%8C%E7%84%B6%E5%90%8E%E5%87%A1%E6%98%AFInnoDB%E5%AD%98%E5%82%A8%E5%BC%95%E6%93%8E%E9%9C%80%E8%A6%81%E7%94%A8%E5%88%B0%E8%BF%99%E4%B8%AA%E7%B4%A2%E5%BC%95%E7%9A%84%E6%97%B6%E5%80%99%EF%BC%8C%E9%83%BD%E4%BC%9A%E4%BB%8E%E9%82%A3%E4%B8%AA%E5%9B%BA%E5%AE%9A%E7%9A%84%E5%9C%B0%E6%96%B9%E5%8F%96%E5%87%BA%E6%A0%B9%E8%8A%82%E7%82%B9%E7%9A%84%E9%A1%B5%E5%8F%B7%EF%BC%8C%E4%BB%8E%E8%80%8C%E6%9D%A5%E8%AE%BF%E9%97%AE%E8%BF%99%E4%B8%AA%E7%B4%A2%E5%BC%95%E3%80%82**%0A%0A%23%23%23%23%202.%20%E5%86%85%E8%8A%82%E7%82%B9%E4%B8%AD%E7%9B%AE%E5%BD%95%E9%A1%B9%E8%AE%B0%E5%BD%95%E7%9A%84%E5%94%AF%E4%B8%80%E6%80%A7%0A%0A%E4%B8%BA%E4%BA%86%E8%AE%A9%E6%96%B0%E6%8F%92%E5%85%A5%E8%AE%B0%E5%BD%95%E8%83%BD%E6%89%BE%E5%88%B0%E8%87%AA%E5%B7%B1%E5%9C%A8%E9%82%A3%E4%B8%AA%E9%A1%B5%E9%87%8C%EF%BC%8C%E6%88%91%E4%BB%AC%E9%9C%80%E8%A6%81%E4%BF%9D%E8%AF%81%E5%9C%A8B%2B%E6%A0%91%E7%9A%84%E5%90%8C%E4%B8%80%E5%B1%82%E5%86%85%E8%8A%82%E7%82%B9%E7%9A%84%E7%9B%AE%E5%BD%95%E9%A1%B9%E8%AE%B0%E5%BD%95%E9%99%A4%E9%A1%B5%E5%8F%B7%E8%BF%99%E4%B8%AA%E5%AD%97%E6%AE%B5%E4%BB%A5%E5%A4%96%E6%98%AF%E5%94%AF%E4%B8%80%E7%9A%84%E3%80%82%E6%89%80%E4%BB%A5%E5%AF%B9%E4%BA%8E%E4%BA%8C%E7%BA%A7%E7%B4%A2%E5%BC%95%E7%9A%84%E5%86%85%E8%8A%82%E7%82%B9%E7%9A%84%E7%9B%AE%E5%BD%95%E9%A1%B9%E8%AE%B0%E5%BD%95%E7%9A%84%E5%86%85%E5%AE%B9%E5%AE%9E%E9%99%85%E4%B8%8A%E6%98%AF%E7%94%B1%E4%B8%89%E4%B8%AA%E9%83%A8%E5%88%86%E6%9E%84%E6%88%90%E7%9A%84%EF%BC%9A%0A%0A*%20%E7%B4%A2%E5%BC%95%E5%88%97%E7%9A%84%E5%80%BC%0A*%20%E4%B8%BB%E9%94%AE%E5%80%BC%0A*%20%E9%A1%B5%E5%8F%B7%0A%0A%23%23%23%23%203.%20%E4%B8%80%E4%B8%AA%E9%A1%B5%E9%9D%A2%E6%9C%80%E5%B0%91%E5%AD%98%E5%82%A82%E6%9D%A1%E8%AE%B0%E5%BD%95%0A%0A%0A%0A%23%23%23%23%20%E7%B4%A2%E5%BC%95%E5%9F%BA%E6%9C%AC%E8%AF%AD%E6%B3%95%0A%0A1.%20%E5%88%9B%E5%BB%BA%E8%A1%A8%E7%9A%84%E6%97%B6%E5%80%99%E6%8C%87%E5%AE%9A%E9%9C%80%E8%A6%81%E5%BB%BA%E7%AB%8B%E7%B4%A2%E5%BC%95%E7%9A%84%E5%8D%95%E4%B8%AA%E5%88%97%E6%88%96%E8%80%85%E5%BB%BA%E7%AB%8B%E8%81%94%E5%90%88%E7%B4%A2%E5%BC%95%E7%9A%84%E5%A4%9A%E4%B8%AA%E5%88%97%EF%BC%9A%0ACREATE%20TALBE%20%E8%A1%A8%E5%90%8D%20(%20%0A%20%20%20%20%E5%90%84%E7%A7%8D%E5%88%97%E7%9A%84%E4%BF%A1%E6%81%AF%20%C2%B7%C2%B7%C2%B7%20%2C%0A%20%20%20%20%5BKEY%7CINDEX%5D%20%E7%B4%A2%E5%BC%95%E5%90%8D%20(%E9%9C%80%E8%A6%81%E8%A2%AB%E7%B4%A2%E5%BC%95%E7%9A%84%E5%8D%95%E4%B8%AA%E5%88%97%E6%88%96%E5%A4%9A%E4%B8%AA%E5%88%97)%20%0A%20)%EF%BC%9B%0A%0A2.%20%E4%BF%AE%E6%94%B9%E8%A1%A8%E7%BB%93%E6%9E%84%E7%9A%84%E6%97%B6%E5%80%99%E6%B7%BB%E5%8A%A0%E7%B4%A2%E5%BC%95%EF%BC%9A%0AALTER%20TABLE%20%E8%A1%A8%E5%90%8D%20ADD%20%5BINDEX%7CKEY%5D%20%E7%B4%A2%E5%BC%95%E5%90%8D%20(%E9%9C%80%E8%A6%81%E8%A2%AB%E7%B4%A2%E5%BC%95%E7%9A%84%E5%8D%95%E4%B8%AA%E5%88%97%E6%88%96%E5%A4%9A%E4%B8%AA%E5%88%97)%EF%BC%9B%0A%0A3.%20%E4%BF%AE%E6%94%B9%E8%A1%A8%E7%BB%93%E6%9E%84%E7%9A%84%E6%97%B6%E5%80%99%E5%88%A0%E9%99%A4%E7%B4%A2%E5%BC%95%EF%BC%9A%0AALTER%20TABLE%20%E8%A1%A8%E5%90%8D%20DROP%20%5BINDEX%7CKEY%5D%20%E7%B4%A2%E5%BC%95%E5%90%8D%EF%BC%9B</center></span>
</div></body></html> 